Process for producing alkyd resins

ABSTRACT

Alkyd resins, processes for their production, and their use are disclosed, these resins being distinguished by the fact that, in production, no organic solvents are used. The alkyd resins are clear and almost odorless and have a low viscosity. When used as a bonding agent in brush paints final products produced from these resins should not contain more than 10 to 15% by weight of organic solvents. The alkyd resins are obtainable from the following ingredients: 
     A) 58.90 to 75.25% by weight of drying fatty acids, 
     B) 7.00 to 16.25% by weight of pentaerythritol, 
     B&#39;) 0 to 3.00% by weight of glycerol 
     C) 0.07 to 1.40% by weight of hypophosphorous acid, 
     D) 5.00 to 29.00% by weight of trimellitic anhydride and 
     E) 0 to 5.00% by weight of triphenyl phosphite, where the components A), B), B&#39;), C), and E) must make up 100% by weight.

This is a divisional of co-pending U.S. patent application Ser. No.07/538,311 filed on Jun. 14, 1990 now U.S. Pat. No. 5,158,608 whichapplication is a continuation-in-part of U.S. patent application Ser.No. 07/313,894, filed Feb. 23, 1989, now abandoned and both applicationsare entirely incorporated herein by reference.

BACKGROUND OF THE INVENTION

The present invention relates to alkyd resins, processes for theirproduction, and their use. Such alkyd resins are especially suited formaking environmentally benign paints, varnishes, and pigments.

SUMMARY OF THE INVENTION

The object of the present invention is to provide environmentally benignalkyd resins, which are distinguished by the following properties:

i. no organic solvent is used in the production of the alkyd resins;

ii. the alkyd resins are clear and almost odorless;

iii. the finished solvent-free alkyd resins have such a low viscositythat they can be drawn off in the normal way; and

iv. in the production of coating materials, the alkyd resins, when usedas bonding agents, for example in brush paints for internal and externaluse, do not contain more than 10 to 15% by weight of organic solvents,particularly based on hydrocarbons (white spirit), in order to obtainpaints with high solids content, good brushability, high gloss, gooddrying and good consistency, so that environmentally benign paints(varnishes, pigmented paints) with the given low solvent content areprovided, conforming to the requirements of the Environmental Agency ofGermany in Berlin for recognition by the quality designation "BlauerEngel" (Blue Angel).

This object is successfully achieved as described hereinbelow.

Fatty acids which are suitable for the alkyd resin according to theinvention made from natural linoleic acid-rich drying oils are: soya oilfatty acid, sunflower oil fatty acid, tall oil fatty acid, safflower oilfatty acid, used individually or mixtures thereof.

The objects of this invention may be realized by providing an alkydresin, obtainable from:

A) 58.90 to 75.25% by weight of a monobasic acid, such as drying fattyacids,

B) 7.00 to 16.255 by weight of pentaerythritol,

B') 0 to 3.00% by weight of glycerol,

C) 0.07 to 1.4% by weight of hypophosphorous acid,

D) 5.00 to 29.00% by weight of a polycarboxylic anhydride, such astrimellitic anhydride, and

E) 0 to 5.00% by weight of triphenyl phosphite, where the components A),B), B'), C), D), and E) must make up 100% by weight. The alkyd resinsmay be prepared by heating these ingredients followed by adehydration-condensation.

A resin so produced may be included in an environmentally benign coatingwhich contains no more than 10-15% by weight of organic solvent.

The preferred fatty acids are: tall oil fatty acid; sunflower oil fattyacid; and polyunsaturated fatty acids with an acid number of 198-202, aniodine number of 135-145, a setting point of 4°-8° C., 1% by weight max.of unsaponifiables, a color, measured in a Lovibond 51/4" cell, max.yellow 10.0; red 1.0; chain length distribution % C14-C18=8; C18'=28;C18"=62; C18"'=1; >C18=1; conjugated fatty acids (vegetable) with anacid number of 198-202, an iodine number ≧130 (Wobum Method), a settingpoint ≦16; 1% by weight of unsaponifiables, a color, measured in theLovibond 5 1/4" cell, of yellow 10, red 1.0; approximate fatty acidcomposition saturated C18=13%; saturated and unsaturated C18=1%;unsaturated C18'=24%; C18"=11%; C18"'=0; conjugated C18"=50%; conjugatedC18"'=1%.

In those countries in which tall oil fatty acid is available underparticularly favorable conditions, tall oil fatty acid may be used asthe particularly preferred fatty acid. An embodiment of the inventionutilizing tall oil fatty acid is illustrated by Example 4.

DETAILED DESCRIPTION OF THE INVENTION

The production of the alkyd resins is carried out in reactors which arenormally used in the synthetic resin industry. The components, exceptfor trimellitic anhydride, are added to the reactor and heated totemperatures of 200° C. to 260° C. until the acid number reaches 15,preferably below 10. Generally, a heating time of from 3 to 5 hours isnecessary to accomplish this.

Trimellitic anhydride and optionally triphenyl phosphite are then addedin portions, in the course of 30 to 90 minutes with stirring, thetemperature being maintained. As soon as the reaction is complete, whichusually requires about 3 to 6 hours at 250° C., the reaction mixture,after the usual cooling to about 200° C., can be filtered. The end ofthe reactor can be detected by determination of the acid number. Thisacid number can be as high as 15, but the range below 10 is preferred,and acid numbers are between 5 and 10 are especially preferred.Moreover, at the end of the reaction, the viscosity at 25° C. ismeasured on a sample in an ICI plate-and-cone viscosimeter. Viscositiesbetween 6000 and 2800 mPas/sec. are permissible. The preferred range isfrom 3000 to 3500 mPas/sec.

The process for producing an alkyd resin in accordance with theinvention includes reacting (A) 58.90% to 75.25% by weight of natural,linoleic acid-rich drying fatty acid, (B) 7.00% to 16.25% by weightpentaerythritol, (B') 0 to 3.00% by weight glycerol, and (C) 0.07% to1.4% by weight hypophosphorous acid, in a melt at temperatures in therange of 200° C. to 260° C. until the acid number is below 15.Subsequently, components (D) 5.00 to 29.00% by weight trimelliticanhydride and optionally, (E) 0 to 5.00% by weight triphenyl phosphiteare added in portions, while the reaction temperature is maintaineduntil components (D) and (E) have been incorporated.

The alkyd resins obtained can be converted to a paintable condition asair-drying coating materials, by the addition of 10 to 15% by weight ofsolvent or solvent mixtures which are normally used in the paintindustry.

The coating materials which may be used according to the invention mayoptionally contain pigments, fillers, aids and drying agents. Each ofthe pigments, natural and synthetic, transparent and non-transparent,are suitable for use as pigments in accordance with the invention. Theoptimum proportion of pigment can be easily determined by those skilledin the art.

Examples of suitable drying agents are as follows: metal salts of(cyclo)aliphatic, natural or synthetic acids, such as, linoleic acid,naphthenic acid or 2-ethylhexanoic acid, wherein cobalt, manganese,lead, zirconium, calcium and zinc may be included as suitable metals.Mixtures of siccatives may also be used. Based on the proportion ofmetal, the drying agents are used in a preparation of 0.001 to about 3%by weight, based on the bonding agent solids.

The invention is explained by the following examples below. Theseexamples are intended to be illustrative in nature, not limiting.

EXAMPLE 1

1214 g of sunflower oil fatty acid, 254 g of pentaerythritol and 22 g ofhypophosphorous acid are heated in a flask, fitted with a waterseparator, stirrer and thermometer, under an inert gas to 235° C. andmaintained at this temperature long enough for the acid number to fallto 7.3. Generally, a heating time of about 3 to 4 hours is necessary toattain this acid number. Then, 164 g of trimellitic anhydride is addedin portions of about 30 to 40 grams at intervals of 15 to 30 minutes inthe course of 60 to 220 minutes. After the final addition, thetemperature is maintained at 235° C. long enough for the acid number toreach 15.0. The heating time required after the final addition oftrimellitic anhydride was about 5 hours.

The viscosity of the alkyd resin so produced was 3100 mPas/sec at 25° C.

EXAMPLE 2

900 g of tall oil fatty acid, 357 g of a conjugated fatty acid(vegetable) (as expounded in the description above), 33 g of glycerol,170 g of pentaerythritol and 3 g of hypophosphorous acid are heated in aflask, fitted with a water separator, stirrer and thermometer, under aninert gas to 250° C. and maintained at this temperature until the acidnumber reaches 6.5, for which about 120 minutes is required. Then, 585 gof trimellitic anhydride and 3 g of triphenyl phosphite are added inportions of about 20 g each addition, separated by 10 to 30 minutes, 30to 60 minutes overall. After the final addition, the temperature ismaintained at 250° C. long enough until the acid number reaches 4.9, forwhich 6 to 7 hours is required.

The viscosity of the final product was 3250 mPas/sec at 25° C.

EXAMPLE 3

The following components are added to a synthetic resin reactor: 2014 kgof sunflower oil fatty acid, 421 kg of pentaerythritol, 2 kg ofhypophosphorous acid and 5 g of antifoaming agent.

The reactor is closed and air excluded by continuously purging thereactor with pure nitrogen. For this purpose, nitrogen is passed throughthe reactor vessel at 1 m³ per hour. Then the contents of the reactorare heated to 235° C. and maintained at this temperature long enough forthe acid number to have fallen below 10. Then, a total amount of 272 kgof trimellitic anhydride is fed into the reactor in portions such thatthe entire amount is added within one hour at 235° C., and the contentsof the reactor are further maintained at 235° C. until the acid numberhas fallen below 10. Then the resin is cooled to 80° C. and filtered.2553 kg of alkyd resin is obtained. The viscosity, measured at 25° C.,is 3300 mPas/sec. The acid number is below 10.

EXAMPLE 4

1214 g of tall oil fatty acid (iodine number according to Weiss is atleast 160 and resin content is a maximum of 2% by weight), 254 g ofpentaerythritol and 22 g of hypophosphorous acid are heated in a flask,fitted with a water separator, stirred and thermometer, under an inertgas to 235° C. and maintained at this temperature long enough until theacid number has fallen below 10. Generally, a heating time of 3 to 4hours is required for this. Then 164 g of trimellitic anhydride is addedin portions of about 30 to 40 grams at intervals of 15 to 30 minutesover the course of 60 to 220 minutes. After the final addition, thetemperature is maintained at 235° C. until the acid number is 12.0. Inorder to reach this acid number the reaction mixture must be kept at235° C. for about 7 to 8 hours.

The viscosity of the alkyd resin was 5,000 mPas/sec. at 25° C.

USE EXAMPLE 1

High solids content white brush paint:

The following ingredients are mixed:

    ______________________________________                                        a)   Alkyd resin according to Example 1 (100%)                                                              35.00   kg                                      b)   Titanium dioxide CL 310  40.00   kg                                      c)   Liquid solvent-free dispersant and                                                                     0.50    kg                                           brightening agent. In the preferred                                           embodiment, Borchigen ND is used.                                        ______________________________________                                    

This product is an ionic dispersant product which is free from sulfonicgroups.

    ______________________________________                                        d)  Drying agent. In the preferred                                                                            2.00   kg                                         embodiment Soligen-calcium 10% (a metal soap,                                 namely calcium octoate based on 2-ethyl hexanoic                              acid) is used.                                                            e)  White spirit-Kristallol 60 (K60) in the                                                                   3.00   kg                                         preferred embodiment.                                                     ______________________________________                                    

These ingredients are mixed for 30 minutes in the ball mill, 1:1 withballs, with the addition of the following ingredients:

    ______________________________________                                        f)   Alkyd resin according to Example 1-100%                                                                 15.00  kg                                      g)   Drying agents. In the                                                         preferred embodiment, these are:                                              Soligen-cobalt 6%         0.40   kg                                           Soligen-zirconium-6%      0.7    kg                                      h)   White spirit-Kristallol 60                                                                              1.9    kg                                      i)   Antiskinning agent based on methyl                                                                      0.5    kg                                           ethyl ketoxime-Luaktin 50% in the                                             preferred embodiment                                                     j)   Methylpolysiloxane additive-this is a                                                                   1.0    kg                                           standard lacquer additive. Silicone oil A                                     1% in Kristallol 60 is used in the preferred                                  embodiment.                                                              ______________________________________                                    

100 kilograms of a high solid content white brush paint product isobtained. The final product has the following properties:

    ______________________________________                                        Viscosity/20° C.                                                                           = 350 sec.                                                Total solids content                                                                              = 92.15%                                                  adjusted with 3.3% K60                                                                            = 190 sec.                                                Total solids content                                                                              = 88.8%                                                   Degree of dryness T1                                                                              = 3 hours 50 minutes                                      Degree of dryness T2                                                                              = 4 hours 10 minutes                                      Degree of dryness T3                                                                              = 4 hours 20 minutes                                      Degree of dryness T4                                                                              = 5 hours                                                 Layer thickness     = ca 50 micrometers                                       Leveling            = free of streaks                                         Gloss angle 60°                                                                            = 95%                                                     Color tone          = white                                                   Pendulum hardness/7 days                                                                          = 28 seconds.                                             -23° C.                                                                ______________________________________                                    

USE EXAMPLE 2

High solids content white brush paint:

The following ingredients are mixed:

    ______________________________________                                        a)   Alkyd resin according to Example 1 (100%)                                                               35.00  kg                                      b)   Titanium dioxide CL 310   40.00  kg                                      c)   Liquid solvent-free dispersant and                                                                      0.50   kg                                           brightening agent. In the preferred                                           embodiment, Borchigen ND is used.                                        d)   Drying agent. In the preferred                                                                          2.00   kg                                           embodiment Soligen-calcium 10% is used.                                  e)   White spirit-Kristallol 60 in the                                                                       3.00   kg                                           preferred embodiment.                                                    ______________________________________                                    

These ingredients are mixed for 30 minutes in the ball mill, 1:1 withballs, with the addition of the following ingredients:

    ______________________________________                                        f)   Alkyd resin according to Example 2-100%                                                                 17.50  kg                                      g)   Drying agents. In the preferred embodiment,                                                             0.40   kg                                           Borders octa Soligen drier 69 is used.                                   h)   Methylpolysiloxane additive-this is a                                                                   1.1    kg                                           standard lacquer additive. Silicone oil A                                     1% in Kristallol 60 is used in the preferred                                  embodiment.                                                              i)   Antiskinning agent based on methyl                                                                      0.5    kg                                           ethyl ketoxime-Luaktin 50% in the                                             preferred embodiment.                                                    ______________________________________                                    

100 kilograms of a high solid content white brush paint product isobtained. The final product has the following properties:

    ______________________________________                                        Viscosity/20° C.                                                                          = 400 sec.                                                 adjusted with 4.5% K60                                                                           = 195 sec.                                                 Solids content     = 90.5%                                                    Degree of dryness Tl                                                                             = 4 hours 30 minutes                                       Degree of dryness T2                                                                             = 5 hours                                                  Degree of dryness T3                                                                             = 5 hours 5 minutes                                        Degree of dryness T4                                                                             = 5 hours 10 minutes                                       Layer thickness    = ca 40 micrometers                                        Color tone         = white                                                    Leveling           = free of streaks                                          Gloss angle 60°                                                                           = 96%                                                      Pendulum hardness/7 days                                                                         = 30 sec.                                                  -23° C.                                                                ______________________________________                                    

USE EXAMPLE 3

High solids content white brush paint based on alkyd resin according toExample 3.

The following ingredients are mixed:

    ______________________________________                                        a)  Alkyd resin according to Example 3 (100%)                                                                 35.00  kg                                     b)  Titanium dioxide CL 310     40.00  kg                                     c)  Liquid solvent-free dispersant and                                                                        0.50   kg                                         brightening agent. Borchigen ND is preferred.                             d)  Alkyd resin according to Example 3 (100%)                                                                 15.00  kg                                     e)  Nuodex-Kombi ANE (1.2% Co; 2% Ca; 3.3% Zr)                                                                2.5    kg                                         organic metallic in white spirit                                          f)  White spirit-Kristallol 60  0.50   kg                                     g)  Methylpolysiloxane additive-pre-                                                                          1.00   kg                                         ferrable silicone oil A in 1% Kristallol 60                               h)  Methyl ethyl ketoxime based antiskinning                                                                  0.50   kg                                         agent-preferrably Luaktin 50%                                                 Viscosity/20° C. (measured in a DIN cup with                                                       500    sec                                        4 mm opening)                                                                 + 6% Kristallol 60          180    sec                                    ______________________________________                                    

The unthinned and thinned solids contents are shown below.

    ______________________________________                                        Solids content-unthinned                                                                             = 92.0%                                                Solids content-thinned = 86.8%                                                ______________________________________                                    

Other properties of the final product are as follows:

    ______________________________________                                        Degree of dryness T1                                                                              = 4 hours                                                 Degree of dryness T2                                                                              = 4 hours 5 minutes                                       Degree of dryness T3                                                                              = 4 hours 20 minutes                                      Degree of dryness T4                                                                              = 4 hours 50 minutes                                      Leveling            = free of streaks                                         Gloss at 60° angle                                                                         = 95%                                                     Color tone          = white                                                   Pendulum hardness/7 days                                                                          = ca. 30 seconds                                          -23° C.                                                                spread to 200 micrometers on glass                                                                = free of                                                 with a doctor blade   ripples                                                 ______________________________________                                    

The color tone of the paint product can be shifted toward white byaddition of a pigment toner mask, such as 0.01% of Tint Ayd Al 234 A,available from the Daniel Products Co.

While the invention has been described in conjunction with variousparticular embodiments, modifications and changes may be made withoutdeparting from the spirit and scope of the inventions as defined in thefollowing claims.

I claim:
 1. A process for the production of an alkyd resin, comprising: reactingA) 58.90% to 75.25% by weight of natural, linoleic acid-rich drying fatty acid, B) 7.00% to 16.25% by weight of pentaerythritol, B') 0 to 3.00% by weight of glycerol, C) 0.07% to 1.4% by weight of hypophosphorous acid, in a melt at temperature in the range of 200° C. to 260° C. until the acid number is below 15: and subsequently adding the components, D) 5.00 to 29.00% by weight of trimellitic anhydride and E) 0 to 5.00% by weight of triphenyl phosphite in portions while maintaining the reaction temperature until the components D) and E) have been incorporated.
 2. The process as defined in claim 1, wherein the reaction proceeds until the acid number is below
 10. 3. The process as defined in claim 1, wherein the reaction proceeds until the acid number is in the range of 5 to
 10. 4. The process as defined in claim 1, wherein the viscosity of the components after reaction is in the range of 2800 to 6000 mPas/sec.
 5. The process as defined in claim 1, wherein the viscosity of the components after reaction is in the range of 3000 to 3500 mPas/sec. 